Several Iranian Kurdish rebels based in Iraq were wounded in hours of clashes with Tehran's forces along the two countries' border, a rebel spokesman said on Sunday.
The fighting comes less than a week after the Islamic Republic warned that it reserved the right to attack the bases of the PJAK, or the Party of Free Life of Kurdistan, in neighbouring Iraq's autonomous Kurdish region.
"Since midnight (2100 GMT Saturday), heavy battles have been ongoing between PJAK and the Iranian army, resulting in injuries among elements of our group," rebel spokesman Sherzad Kamankar told AFP.
"The battle has been going on for more than 10 hours continuously, and Iranian artillery is still being fired this morning."
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Kamankar said multiple Iranian soldiers had been killed and wounded in the fighting near the Banjaween area of Iraqi Kurdistan's Sulaimaniyah province, but this could not be independently confirmed.
Jabbar Yawar, the top official in the Iraqi Kurdish ministry responsible for the region's peshmerga security forces, confirmed Iranian shelling of PJAK bases, but said he had received no reports of clashes.
According to Kamankar, Iranian forces have warned villagers living in areas along Iraq's side of the border to vacate their homes within three days. Yawar, however, dismissed the claim as a "rumour".
Iran routinely shells border districts of Iraq's autonomous Kurdish region, targeting PJAK bases, including a July 7 bombardment of Haj Omran.
The shelling came despite a warning on July 3 by the president of Iraqi Kurdistan, Massud Barzani, over the cross-border operations.
On July 11, Iran's official IRNA news agency quoted an unnamed army official as saying Tehran's forces "reserve the right to attack and destroy terrorist bases in border areas".